Preheat the oven to 350°F / 175°C.
Grease two 8-inch layer cake pans or one 9x13-inch rectangular pan with butter.
In a medium bowl, whisk together the flour, baking powder, and salt.
In a large bowl using an electric mixer, beat the 1/2 cup (480 ml) olive oil with 3/4 cup (960 ml) of the sugar until creamy.
Add the egg yolks one at a time, beating well after each addition until the mixture is thick and fluffy, about 5-7 minutes. Scrape down the sides of the bowl as needed.
Gently mix the dry into the wet until just combined and smooth.
Stir in the fresh orange juice and zest until blended.
In a separate, clean bowl, beat the egg whites with an electric mixer until they begin to foam. Gradually sprinkle in the remaining 1/4 cup (960 ml) of sugar while continuing to beat until soft peaks form.
Gently fold about one-third of the beaten egg whites into the thick batter to lighten it.
Then, carefully fold in the remaining egg whites until just incorporated. Be careful not to overmix.
Pour the batter into the prepared pan(s).
Bake for about 35 minutes, or until a toothpick inserted into the center comes out clean.
Let the cake cool in the pan on a wire rack for 15 minutes. If using layer pans, carefully invert the cakes onto the rack to cool completely. If using a rectangular pan, you can let it cool completely in the pan. Frost or glaze once cooled, if desired.
Don't overmix the batter after adding the flour.
Mix just until the streaks of flour disappear to ensure a tender, not tough, crumb.
